The figure appears to be a triangle with the following measures:
Opposite Side = a = 6
Adjacent Side = b = 15
Hypotenuse = c = unknown
To be able to find the measure of the unknown side, since it appears to be a right triangle, we will be using the Pythagorean Formula:
[tex]\text{ c}^2=a^2+b^2[/tex][tex]\text{ c = }\sqrt[]{a^2+b^2}[/tex][tex]\begin{gathered} \text{ c = }\sqrt[]{(6)^2_{}+(15)^2} \\ \end{gathered}[/tex][tex]\text{ = }\sqrt[]{36\text{ + 225}}[/tex][tex]\text{ = }\sqrt[]{261}[/tex][tex]\text{ c = }\sqrt[]{261}\text{ = 16.1554944214}[/tex]